Programming Fundamentals Using C

141 Pages·2007·1.82 MB·English

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PROGRAMMING FUNDAMENTALS
USING “C”
Subject: PROGRAMMING FUNDAMENTALS USING “C” Credits: 4

SYLLABUS

Introduction to „C‟ Language
Structures of ‘C’ Programming. Constants and Variables, C Tokens, Operators, Types of operators, Precedence
and Associativity, Expression , Statement and types of statements

Built-in Operators and function
Console based I/O and related built-in I/O function, Concept of header files, Preprocessor directives, Decision
Control structures, The if Statement, Use of Logical Operators, The else if Clause.

Loop Control structures
Nesting of loops , Case Control Structure, using Switch Introduction to problem solving, Problem solving
techniques (Trial & Error, Brain storming, Divide & Conquer), Steps in problem solving (Define Problem,
Analyze Problem, Explore Solution), Algorithms and Flowcharts (Definitions, Symbols), Characteristics of an
algorithm

Simple Arithmetic Problems
Addition / Multiplication of integers, Functions, Basic types of function, Declaration and definition, Function
call, Types of function, Introduction to Pointers, Pointer Notation, Recursion.

Storage Class
Automatic Storage Class , Register Storage Class, Static Storage Class, External Storage Class

Suggested Readings:

1. Mastering C by Venugopal, Prasad – TMH
2. Complete reference with C Tata McGraw Hill
3. C – programming E.Balagurusamy Tata McGray Hill
4. How to solve it by Computer : Dromey, PHI
5. Schaums outline of Theory and Problems of programming with C : Gottfried
6. The C programming language : Kerninghan and Ritchie
7. Programming in ANSI C : Ramkumar Agarwal
8. Mastering C by Venugopal, Prasad – TMH
9. Let Us C by Kanetkar
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COURSE OVERVIEW N
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The computing world has undergone a revolution since the Although we have noted the places where the language has
publication of The C Programming Language in 1978. Big evolved, we have chosen to write exclusively in the new form.
computers are much bigger, and personal computers have For the most part, this makes no significant difference; the
capabilities that rival mainframes of a decade ago. During this most visible change is the new form of function declaration and
time, C has changed too, although only modestly, and it has definition. Modern compilers already support most features of
spread far beyond its origins as the language of the UNIX the standard.
operating system.
C is not a big language, and it is not well served by a big book.
The growing popularity of C, the changes in the language over We have improved the exposition of critical features, such as
the years, and the creation of compilers by groups not involved pointers, that are central to C programming. We have refined the
in its design, combined to demonstrate a need for a more original examples, and have added new examples in several
precise and more contemporary definition of the language than chapters. For instance, the treatment of complicated declarations
the first edition of this book provided. In 1983, the American is augmented by programs that convert declarations into words
National Standards Institute (ANSI) established a committee and vice versa. As before, all examples have been tested directly,
whose goal was to produce “an unambiguous and machine- which is in machine-readable form.
independent definition of the language C”, while still retaining
As we said in the preface to the C “wears well as one’s experi-
its spirit. The result is the ANSI standard for C.
ence with it grows”. With a decade more experience, we still feel
It provides a new form of function declaration that permits that way. We hope that this book will help you learn C and use
cross-checking of definition with use. It specifies a standard it well.
library, with an extensive set of functions for performing input
and output, memory management, string manipulation, and
similar tasks.
It makes precise the behavior of features that were not spelled
out in the original definition, and at the same time states
explicitly which aspects of the language remain machine-
dependent.
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CONTENT

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Lesson 1 Concepts of Data storage within a computer program 1 AT
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Lesson 2 Concept of variable, constant and preprocessor U
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directive statements. 4 IN
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Lesson 3 Elements of Language : Expressions, Statements, Operators 10 ‘
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Lesson 4 Binary & Relational Operators 13
Lesson 5 Branching Constructs 15
Lesson 6 Precedence of Operators 19
Lesson 7 Controlling Program Execution 23
Lesson 8 While & Do While Loop 30
Lesson 9 Break Statement 33
Lesson 10 Switch Statement 38
Lesson 11 Functions 43
Lesson 12 Writing a Function 47
Lesson 13 Function Prototype & Recursive Function 51
Lesson 14 Introduction to Arrays 55
Lesson 15 Naming and Declaring Arrays 58
Lesson 16 Types of I/O & Console I/O Functions 63
Lesson 17 Escape Sequences 66
Lesson 18 Formatted output conversion specifiers 70
Lesson 19 Character Input &Character Output 73
Lesson 20 Stream I/O 76
Lesson 21 Scope of Veriables 80
Lesson 22 Scope of Function Parameters 84
Lesson 23 Input and Output Redirection 88
Lesson 24 Command Line Arguments 92
Lesson 25 Introduction to Structures and Unions 94
Lesson 26 Arrays of Structures 99
Lesson 27 Introduction to typedef & Macro 104
Lesson 28 Details of Unions 107
Lesson 29 Introductions to Bits & Its Operators 112
Lesson 30 Dynamic Memory Allocation 114
Lesson 31 Functions of Dynamic Memory Allocation 118
Lesson 32 Verification and Validation 122
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Lesson 33 Testing strategies 126
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Lesson 35 Types of Errors 134
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LESSON 1 R
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CONCEPTS OF DATA STORAGE WITHIN A COMPUTER PROGRAM
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Objectives One typewritten page Approximately 3,000 F
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The RAM in your computer is organized sequentially, one byte N
• Know how the computer memory is organized. D
following another. Each byte of memory has a unique address A
• Know about the memory space required to store data M
by which it is identified—an address that also distinguishes it
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• Know what a variable is? And the different types of variables from all other bytes in memory. Addresses are assigned to N
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Computer programs usually work with different types of data memory locations in order, starting at zero and increasing to the AL
and need a way to store the values being used. These values can system limit. For now, you don’t need to worry about ad- S
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be numbers or characters. C has two ways of storing number dresses; it’s all handled automatically by the C compiler. S
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values—variables and constants—with many options for each. What is your computer’s RAM used for? It has several uses, but G
A variable is a data storage location that has a value that can only data storage need concern you as a programmer. Data is the ‘
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change during program execution. In contrast, a constant has a information with which your C program works. Whether your ’
fixed value that can’t change. program is maintaining an address list, monitoring the stock
Today you will learn: market, keeping a household budget, or tracking the price of
hog bellies, the information (names, stock prices, expense
• How to create variable names in C
amounts, or hog futures) is kept in your computer’s RAM
• The use of different types of numeric variables
while the program is running.
• The differences and similarities between character and
Now that you understand a little about the nuts and bolts of
numeric values
memory storage, you can get back to C programming and how
• How to declare and initialize numeric variables C uses memory to store information.
• C’s two types of numeric constants Variables
• Before you get to variables, however, you need to know a A variable is a named data storage location in your computer’s
little about the operation of your computer’s memory. memory. By using a variable’s name in your program, you are, in
effect, referring to the data stored there.
Computer Memory
If you already know how a computer’s memory operates, you Variable Names
can skip this section. If you’re not sure, however, read on. This To use variables in your C programs, you must know how to
information will help you better understand certain aspects of C create variable names. In C, variable names must adhere to the
programming. following rules:
A computer uses random-access memory (RAM) to store • The name can contain letters, digits, and the underscore
information while it’s operating. RAM is located in integrated character (_).
circuits, or chips, inside your computer. RAM is volatile, which • The first character of the name must be a letter. The
means that it is erased and replaced with new information as underscore is also a legal first character, but its use is not
often as needed. Being volatile also means that RAM “remem- recommended.
bers” only while the computer is turned on and loses its
• Case matters (that is, upper- and lowercase letters). Thus, the
information when you turn the computer off.
names count and Count refer to two different variables.
Each computer has a certain amount of RAM installed. The
• C keywords can’t be used as variable names. A keyword is a
amount of RAM in a system is usually specified in kilobytes
word that is part of the C language. (A complete list of 33 C
(KB) or megabytes (MB), such as 512KB, 640KB, 2MB, 4MB, or
keywords can be found in Appendix B, “Reserved Words.”)
8MB. One kilobyte of memory consists of 1,024 bytes. Thus, a
system with 640KB of memory actually has 640 * 1,024, or The following list contains some examples of legal and illegal C
65,536, bytes of RAM. One megabyte is 1,024 kilobytes. A variable names:
machine with 4MB of RAM would have 4,096KB or 4,194,304 Variable Name Legality
bytes of RAM.
Percent Legal
The byte is the fundamental unit of computer data storage. y2x5__fg7h Legal
Memory space required to store data. annual_profit Legal
Data Bytes Required _1990_tax Legal but not advised
The letter x 1 savings#account Illegal: Contains the illegal character #
The number 500 2 double Illegal: Is a C keyword
The number 241.105 4
9winter Illegal: First character is a digit
The phrase Teach Yourself C 17
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P Because C is case-sensitive, the names percent, PERCENT, and • Integer variables come in two flavors: signed integer variables
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Using all-uppercase letters is usually reserved for the names of part (that is, real numbers).
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F For many compilers, a C variable name can be up to 31 charac- types. These are summarized in the table given below. It also
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flexibility, you can create variable names that reflect the data 16-bit architecture.
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T Table. C’s numeric data types.
A payments could store the value of the prime interest rate in a
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NG even Johnny Carson; it doesn’t matter to the C compiler. The Integer int 2 -32768 to 32767
‘C use of the variable, however, wouldn’t be nearly as clear to Short integer short 2 -32768 to 32767
’ someone else looking at the source code. Although it might
Long integer long 4 -7,483,648
take a little more time to type descriptive variable names, the
improvements in program clarity make it worthwhile. to2,147,438,647
Many naming conventions are used for variable names created Unsigned unsigned 1 0 to 255
from multiple words. character char
You’ve seen one style: Unsigned unsigned 2 0 to 65535
integer int
interest_rate. Using an underscore to separate words in a
variable name makes it easy to interpret. The second style is Unsigned unsigned 2 0 to 65535
called camel notation. Instead of using spaces, the first letter of short integer short
each word is capitalized. Instead of interest_rate, the variable Unsigned unsigned 4 0 to 4,294,
would be named InterestRate. Camel notation is gaining long integer long 967,295
popularity, because it’s easier to type a capital letter than an
Single- Float 4 1.2E-38
underscore. We use the underscore in this book because it’s
precision to3.4E381
easier for most people to read. You should decide which style
floating-point
you want to adopt.
Double- Double 8 2.2E-308
• DO use variable names that are descriptive.
precision f to1.8E3082
• DO adopt and stick with a style for naming your variables. loating-point
• DON’T start your variable names with an underscore 1. Approximate range; precision = 7 digits
unnecessarily.
2. Approximate range; precision = 19 digits.
• DON’T name your variables with all capital letters Approximate range means the highest and lowest values a given
unnecessarily. variable can hold. (Space limitations prohibit listing exact ranges
Numeric Variable Types for the values of these variables.)
Precision means the accuracy with which the variable is stored.
C provides several different types of numeric variables. You
(For example, if you evaluate 1/3, the answer is 0.33333... with
need different types of variables because different numeric
3s going to infinity. A variable with a precision of 7 stores seven
values have varying memory storage requirements and differ in
3s.)
the ease with which certain mathematical operations can be
performed on them. Looking at Table, you might notice that the variable types int
and short are identical. Why are two different types necessary?
Small integers (for example, 1, 199, and -8) require less memory
The int and short variable types are indeed identical on 16-bit
to store, and your computer can perform mathematical
IBM PC-compatible systems, but they might be different on
operations (addition, multiplication, and so on) with such
other types of hardware. On a VAX system, a short and an int
numbers very quickly. In contrast, large integers and floating-
aren’t the same size. Instead, a short is 2 bytes, whereas an int is
point values (123,000,000 or 0.000000871256, for example)
4. Remember that C is a flexible, portable language, so it
require more storage space and more time for mathematical
provides different keywords for the two types. If you’re
operations. By using the appropriate variable types, you ensure
working on a PC, you can use int and short interchangeably.
that your program runs as efficiently as possible.
No special keyword is needed to make an integer variable
C’s numeric variables fall into the following two main catego-
signed; integer variables are signed by default. You can, how-
ries:
ever, include the signed keyword if you wish. The keywords
• Integer variables hold values that have no fractional part (that
is, whole numbers only).
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shown in Table are used in variable declarations, which are P
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• The size of a short is less than or equal to the size of an int. IN
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• The size of an int is less than or equal to the size of a long. L
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F Objectives 8. Define a constant called GST with a value of .125
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ND • Know how to declare a variable. #define GST 0.125
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EN • Know what a constant is? And the different types of The typedef keyword is used to create a new name for an
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‘C declared. A variable declaration tells the compiler the name and define variables of type int, as in this example:
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type of a variable and optionally initializes the variable to a
integer count;
specific value. If your program attempts to use a variable that
Note that typedef doesn’t create a new data type; it only lets you
hasn’t been declared, the compiler generates an error message. A
use a different name for a predefined data type.
variable declaration has the following form:
The most common use of typedef concerns aggregate data
typename varname;
types, “Structures.”
typename specifies the variable type and must be one of the
An aggregate data type consists of a combination of data types
keywords listed in Table varname is the variable name, which
presented in this lesson.
must follow the rules mentioned earlier.
Initializing Numeric Variables
You can declare multiple variables of the same type on one line
When you declare a variable, you instruct the compiler to set
by separating the variable names with commas:
aside storage space for the variable. However, the value stored in
int count, number, start; /* three integer variables */
that space—the value of the variable—isn’t defined. It might be
float percent, total; /* two float variables */ zero, or it might be some random “garbage” value. Before
When we learn about “Understanding Variable Scope,” you’ll using a variable, you should always initialize it to a known
learn that the location of variable declarations in the source code value. You can do this independently of the variable declaration
is important, because it affects the ways in which your program by using an assignment statement, as in this example:
can use the variables. For now, you can place all the variable int count; /* Set aside storage space for count */
declarations together just before the start of the main()
count = 0; /* Store 0 in count */
function.
Note that this statement uses the equal sign (=), which is C’s
Excercise
assignment operator. The one in programming is not the same
1. Declare an integer called sum as the equal sign in algebra. If you write x = 12in an algebraic
int sum; statement, you are stating a fact:
2. Declare a character called letter “x equals 12.”
char letter; In C, however, it means something quite different: “Assign the
value 12 to the variable named x.”
3. Define a constant called TRUE which has a value of 1
You can also initialize a variable when it’s declared. To do so,
#define TRUE 1
follow the variable name in the declaration statement with an
4. Declare a variable called money which can be used to hold
equal sign and the desired initial value:
currency
int count = 0;
float money;
double percent = 0.01, taxrate = 28.5;
5. Declare a variable called arctan which will hold scientific
Be careful not to initialize a variable with a value outside the
notation values (+e)
allowed range. Here are two examples of out-of-range
double arctan;
initializations:
6. Declare an integer variable called total and initialise it to zero.
int weight = 100000;
int total;
unsigned int value = -2500;
total = 0;
The C compiler doesn’t catch such errors. Your program might
7. Declare a variable called loop, which can hold an integer value. compile and link, but you might get unexpected results when
int loop; the program is run.
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• DO understand the number of bytes that variable types take 1.23E2 1.23 times 10 to the 2nd power, or 123 P
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for your computer. 4.08e6 4.08 times 10 to the 6th power, or 4,080,000 O
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• DO use typedef to make your programs more readable. 0.85e-4 0.85 times 10 to the -4th power, or 0.000085 RA
• DO initialize variables when you declare them whenever A constant written without a decimal point is represented by MM
possible. the compiler as an integer number. Integer constants can be IN
• DON’T use a variable that hasn’t been initialized. Results written in three different notations: G

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can be unpredictable. A constant starting with any digit other than 0 is interpreted as a U
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• DON’T use a float or double variable if you’re only storing decimal integer (that is, the standard base-10 number system). D
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• DON’T try to put numbers into variable types that are too leading minus or plus sign. (Without a leading minus or plus, a EN
small to hold them. constant is assumed to be positive.) AT
• DON’T put negative numbers into variables with an • A constant starting with the digit 0 is interpreted as an octal LS

unsigned type. integer (the base-8 number system). Octal constants can US
contain the digits 0 through 7 and a leading minus or plus IN
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same, as they are known by their name. You know it as sign. ‘
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something, which has fixed value, and it is the same here. • A constant starting with 0x or 0X is interpreted as a ’
hexadecimal constant (the base-16 number system).
Constants
• Hexadecimal constants can contain the digits 0 through 9,
Like a variable, a constant is a data storage location used by your
the letters A through F, and a leading minus or plus sign.
program. Unlike a variable, the value stored in a constant can’t
be changed during program execution. C has two types of Now let us see what a symbolic constant is?
constants, each with its own specific uses. Symbolic Constants
Literal Constants A symbolic constant is a constant that is represented by a name
(symbol) in your program. Like a literal constant, a symbolic
A literal constant is a value that is typed directly into the source
constant can’t change. Whenever you need the constant’s value
code wherever it is needed. Here are two examples:
in your program, you use its name as you would use a variable
int count = 20;
name. The actual value of the symbolic constant needs to be
float tax_rate = 0.28; entered only once, when it is first defined.
The 20 and the 0.28 are literal constants. The preceding state- Symbolic constants have two significant advantages over literal
ments store these values in the variables count and tax_rate. constants, as the following example shows.
Note that one of these constants contains a decimal point, • Suppose that you’re writing a program that performs a
whereas the other does not. The presence or absence of the
variety of geometrical calculations. The program frequently
decimal point distinguishes floating-point constants from
needs the value ,, (3.14159) for its calculations. (You might
integer constants.
recall from geometry class that ,, is the ratio of a circle’s
A literal constant written with a decimal point is a floating-point circumference to its diameter.) For example, to calculate the
constant and is represented by the C compiler as a double- circumference and area of a circle with a known radius, you
precision number. Floating-point constants can be written in could write
standard decimal notation, as shown in these examples:
Circumference = 3.14159 * (2 * radius);
123.456
Area = 3.14159 * (radius)*(radius);
0.019
The asterisk (*) is C’s multiplication operator. Thus, the first of
100. these statements means
Note that the third constant, 100., is written with a decimal “Multiply 2 times the value stored in the variable radius, and
point even though it’s an integer (that is, it has no fractional then multiply the result by 3.14159. Finally, assign the result to
part). The decimal point causes the C compiler to treat the the variable named circumference.”
constant as a double-precision value.
If, however, you define a symbolic constant with the name PI
Without the decimal point, it is treated as an integer constant. and the value 3.14, you could write
Floating-point constants also can be written in scientific
circumference = PI * (2 * radius);
notation. You might recall from high school mathematics that
area = PI * (radius)*(radius);
scientific notation represents a number as a decimal part
multiplied by 10 to a positive or negative power. The resulting code is clearer. Rather than puzzling over what the
value 3.14 is for, you can see immediately that the constant PI is
Scientific notation is particularly useful for representing
being used.
extremely large and extremely small values. In C, scientific
notation is written as a decimal number followed immediately • The second advantage of symbolic constants becomes
by an E or e and the exponent: apparent when you need to change a constant. Continuing
with the preceding example, you might decide that for greater
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